Catalyst composition for the hydrogenation of carboxylic acid esters

ABSTRACT

Disclosed are catalyst compositions comprised of chemically-mixed, copper-titanium oxides and the use of such catalyst compositions in the hydrogenation of certain esters to obtain the alcohol corresponding to the acid residue of the ester.

This is a divisional of copending application Ser. No. 07/309,641 filedon Feb. 13, 1989, now U.S. Pat. No. 4,929,777.

This invention concerns certain novel chemically-mixed, copper-titaniumoxide catalysts and the use of such catalysts in hydrogenatingcarboxylic acid esters to the alcohol which is analagous to thecarboxylic acid portion of the ester.

Processes for the hydrogenation of carboxylic acid esters (referred toherein simply as esters) to alcohols is of significant commercialimportance. For example, dimethyl succinate can be hydrogenated to1,4-butanediol and dimethyl 1,4-cyclohexanedicarboxylate can behydrogenated to 1,4-cyclohexanedimethanol. Both of these diols are usedin substantial quantities in the manufacture of polyesters from whichvarious molded articles and fibers are made. Another example is themanufacture of long chain alcohols by the hydrogenation of natural fats,i.e., glyceryl esters of long chain fatty acids.

Catalysts normally used in the hydrogenation of esters to producealcohols generally require extremely high pressures, e.g., greater than4000 pounds per square inch (psi), to achieve commercially-feasiblerates of conversion to the desired alcohol. The most commonly employedcatalyst in such hydrogenations is copper chromite.

We have discovered that chemically-mixed, copper-titanium oxidecompositions are superior catalysts in processes for hydrogenatingesters to alcohols. These catalytic compositions represent a substantialimprovement over known ester hydrogenation catalysts in that theycatalyze the hydrogenation of esters at satisfactory conversion ratesand selectivity at pressures significantly below 4000 psi, typicallybelow 2500 psi. Moreover, our novel catalyst compositions do not containtoxic metals such as nickel or chromium and thus they are safer tomanufacture and present fewer environmental problems and occupationalhazards in their use and disposal.

The catalyst compositions provided by this invention comprisechemically-mixed, copper-titanium oxides, i.e., a composition whichcontains --Ti--O--Cu-- bonds. These chemically-mixed oxide compositionsmay contain from 1 to about 75 weight percent copper oxide (calculatedas CuO). However, catalytic activity for ester hydrogenation, especiallywhen using the preferred conditions of temperature and pressure asdescribed hereinbelow, is unsatisfactory when the copper oxide contentof the compositions is below about 3, or above about 65, weight percent.Consequently, the copper oxide content of our novel catalystcompositions normally will be in the range of about 3 to 65 weightpercent, based on the weight of the chemically-mixed, copper-titaniumoxides. The preferred compositions contain about about 8.8 to 44.0weight percent copper oxide (same basis).

The essential ingredient, i.e., the chemically-mixed, copper-titaniumoxides, of the novel catalyst compositions may be further defined by theformula

    Cu.sub.x Ti.sub.y O.sub.z

wherein x, y, and z represent atomic ratios and x is about 0.01 to 0.75,y is about 0.99 to 0.25 and z is about 1.99 to 1.25. The particularlypreferred catalyst compositions are those wherein x is about 0.09 to0.44, y is about 0.91 to 0.56 and z is about 1.91 to 1.56.

In addition to the mixed copper-titanium oxides, the catalystcompositions may contain or be deposited on or in other materials. Asour catalysts are developed for use in specific process, it may beadvantageous to add minor amounts, e.g., up to about 10 weight percent,of other elements such as Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, La, Ce orpossibly others to the catalyst compositions to increase their lifetimesin commercial operations or to modify their activity and selectivity. Italso may be desirable to add "structural promoters" to the catalysts toincrease surface area or to change the acidity/basicity to optimizeperformance of the catalyst in a specific process. Such structuralpromoters as the oxides of silicon, aluminum, germanium, boron, tin,zinc etc. can be combined with the catalysts during their preparation,replacing part of the titanium component but maintaining theconcentration of the copper oxide in the catalysts, which may alsocontain an oxide of lanthanum or zinc, within the range of about 3 to 65weight percent. Alternatively, the catalysts may be deposited on suchoxides, for example, by preparing the catalysts in the presence of suchan oxide of a particular shape or particle size.

Our novel catalyst compositions can be used in the form of powders,cylinders, spheres, honeycombs, etc., the physical form being dictatedby the type of reactor chosen for and by economic and engineeringconsiderations associated with a particular hydrogenation process.Frequently, it will be desirable to use a binder to assist in theformation and maintenance of the catalyst compositions in a particularshape. For example, alumina, clays and zirconia are commonly usedbinders in the manufacture of commercial catalyst pellets or cylinders.

The catalyst compositions of this invention may be prepared by a varietyof methods. Generally, suitable procedures are described in Volumes 1and 3 of Studies in Surface Science and Catalysis, Elsevier ScientificPublishing Company. The source of the titanium component of ourcatalysts may be titanium tetrachloride, tetraisopropyl titanate,titania sol, titanium bromide, titanium butoxide, titanium methoxide,titanium butoxy-bis-(2,4-pentanedionate), titanium oxides, etc.Compounds which may be used as the source of the copper componentinclude copper chloride, copper bromide, copper acetate, copperethoxide, copper hydroxide, copper nitrate, copper gluconate, copperpentanedionate, copper oxides, etc.

The titanium and copper compounds may be physically mixed, heated in airat temperatures above 500° C., ground and then reheated. Whereappropriate, hydrous titania can be precipitated and treated with asoluble copper salt such as a chloride, bromide, acetate or nitratefollowed by drying and calcining in air at 550° C. Another procedurecomprises coating a soluble copper compound onto the surface of anamorphous form of titanium oxide (hydrous oxide), followed by calciningin air. The exact method of preparation is not critical so long as theformation of --Ti--O--Cu-- is achieved. This bonding distinguishes theessential or active ingredient of our catalysts from those in whichcopper is merely deposited on the surface of a support and existsprimarily as a --Cu--O--Cu-- species. Other elements or compounds, suchas those specified hereinabove, may be added to the titanium and coppersources during preparation of the catalyst.

The esters which may be hydrogenated in accordance with the processprovided by this invention are aliphatic, cycloaliphatic and aromaticesters of aliphatic and cycloaliphatic mono- and poly-carboxylic acids.The carboxylic acid residue of the ester reactants is not important toour process provided that each oxycarbonyl group hydrogenated is bondedto an aliphatic or cycloaliphatic carbon atom. For example, esters ofarylcarboxylic acids such as alkyl benzoates are not included in theester reactants in our process whereas esters of aralkylcarboxyl acidssuch as alkyl phenylacetates are included within the meaning of estersof aliphatic acids. The aliphatic acid residues may be straight- orbranched-chain, saturated or unsaturated and unsubstituted orsubstituted, for example with a wide variety of substituents such ashalogen, hydroxy, alkoxy, amino, substituted amino, acylamido, aryl,cycloalkyl, etc. The main chain of the aliphatic acid residues maycontain hetero atoms such as oxygen, sulfur and nitrogen atoms.

Typically, the ester reactants employed in our process may contain up toabout 40 carbon atoms. Examples of the carboxylic acid esters includethe aliphatic, cycloaliphatic and aromatic esters of acetic, propionic,butyric, valeric, hexanoic, heptanoic, octanoic, nonanoic, decanoic,undecanoic, lauric, tridecanoic, myristic, pentadecanoic, palmitic,heptadecanoic, stearic, oleic, linoleic, linolenic, nonadecanoic,eicosanoic, arachidonic, heneicosanoic, docosanoic, tetracosanoic,octacosanoic, triacontanoic, dotriacontanoic, acrylic, methacrylic,crotonic, 3-butenoic, cyclobutanecarboxylic, 2-norbornanecarboxylic,malonic, succinic, glutaric, maleic, glutaconic, adipic, pimelic,suberic, azelaic, sebacic, 1,2,4-hexanetricarboxylic, 1,2-, 1,3-, and1,4-cyclohexanedi- carboxylic, 2,6- and2,7-octahydronaphthalenedicarboxylic, 3-[(2-carboxyethyl)thio]butyric,etc. The alcohol segment of the ester reactants may be the residue ofany mono- or poly-hydroxy compound such as methanol, ethanol, butanol,2-butanol, 2-ethylhexanol, 2,2-dimethyl-1,3-propanediol, ethyleneglycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol,1,10-decanediol, cyclohexanol, benzyl alcohol, diethylene glycol,glycerin, trimethylolpropane, phenol, hydroquinone, etc. Thehydrogenation process provided by our invention is particularly usefulfor converting lower, i.e., C₁ -C₄, alkyl esters, especially methylesters, of C₁₀ -C₂₀ carboxylic acids and cyclohexanedicarboxylic acids,e.g., dimethyl 1,4-cyclohexanedi- carboxylic acid.

The amount of catalyst required can be varied substantially depending ona number of factors such as, for example, the composition of thecatalyst and the hydrogenation conditions being used. Furthermore, incertain modes of operation such as trickle bed or vapor phase processesusing a fixed bed of catalyst, the amount of catalyst present relativeto the ester reactant is difficult to define with any degree ofprecision.

The hydrogenation conditions of pressure and temperature also can bevaried depending not only on one another but also the activity of thecatalyst, the mode of operation, selectivity considerations and thedesired rate of conversion. Esters may be hydrogenated to theircorresponding alcohols according to our novel process using temperaturesin the range of about 150° to 350° C. and hydrogen pressures in therange of about 500 to 6000 psi. However, since hydrogenation ratesgenerally increase with temperature, it is normally desirable to operatein the range of about 200° to 300° C. range to maximize both conversionrates and utilization of the commercial hydrogenation facility. Whilerates and conversions generally also increase with increasing pressure,the energy costs for compression of hydrogen, as well as the increasedcost of high-pressure equipment render the use of the lowest pressurepractical very advantageous. Thus, a highly attractive feature of ournovel process is the use of hydrogen pressures below 3000 psi,especially in the range of about 600 to 2000 psi, which give good ratesof conversion, especially when used in conjunction with a hydrogenationtemperature in the range of about 250° to 300° C.

The ester hydrogenation process of this invention may be carried out inthe absence or presence of an inert solvent, i.e., a solvent for theester being hydrogenated which does not affect significantly theactivity of the catalyst and does not react with the hydrogenationproduct or products. Examples of such solvents include alcohols such asethanol and lauryl alcohol; glycols such as mono-, di- and tri-ethyleneglycol; hydrocarbons such as hexane, cyclohexane, octane and decane; andaromatic ethers such as diphenyl ether, etc.

The hydrogenation process may be carried out as a batch, semi-continuousor continuous process. In batch operation a slurry of the catalyst inthe reactant and/or an inert solvent in which the reactant has beendissolved is fed to a pressure vessel equipped with means for agitation.The pressure vessel then is pressurized with hydrogen to a predeterminedpressure followed by heating to bring the reaction mixture to thedesired temperature. After the hydrogenation is complete the reactionmixture is removed from the pressure vessel, the catalyst is separatedby filtration and the product is isolated, for example, in adistillation train.

Continuous operation can utilize a fixed bed using a larger particlesize of catalyst, e.g., catalyst pellets. The catalyst bed may be fixedin a tubular or columnar, high pressure reactor and the liquid reactant,dissolved in an inert solvent if necessary or desired, slowly fedcontinuously above the bed at elevated pressure and temperature andcrude product removed from the base of the reactor. Alternatively, thedescribed fixed-bed catalyst system may be used in a gas-phase mode ofoperation wherein a reactant, which is sufficiently volatile under thehydrogenation conditions, is vaporized and passed through the catalystbed, the off-gas is condensed and the product is isolated. Another modeof continuous operation utilizes a slurry of the catalyst in an agitatedpressure vessel which is equipped with a filter leg to permit continuousremoval of a solution of product in unreacted ester and/or an inertsolvent. In this manner a liquid reactant or reactant solution can becontinuously fed to and product solution continuously removed from anagitated pressure vessel containing an agitated slurry of the catalyst.

Our novel catalyst compositions and hydrogenation process are furtherillustrated by the following examples.

PREPARATION OF CATALYST COMPOSITIONS EXAMPLE 1

Titanium tetraisopropoxide (172.1 g, 0.61 mol) was added dropwise to 500mL water with rapid stirring. After the addition was complete, theslurry was stirred an additional hour. The solid was filtered and washedby reslurrying in water and filtering a second time. The solid was thenreslurried in about 500 mL of water and the pH was adjusted to 10 withconcentrated ammonium hydroxide. The slurry then was heated, withstirring, to and held at 60° C. for three hours. The slurry was cooledwith stirring and filtered. The solids collected were added withstirring to a solution of copper (I) acetate (10.26 g, 0.08 mol) in 450mL water. The resulting slurry was heated, with stirring, to and held at60° C. for three hours. The slurry was cooled to room temperature withstirring and then filtered and washed on the filter with water. Thesolid material collected was dried on a steam bath and then calcined inair for one hour at 200° C., one hour at 350° C. and three hours at 550°C. The catalyst composition thus obtained contained 8.8 weight percentcopper, had a BET surface area of 9 square meters per g (m² /g) and hadthe formula Cu₀.11 Ti₀.89 O₁.89.

EXAMPLE 2

Titanium tetraisopropoxide (71.2 g, 0.25 mol) was added dropwise to 500mL water with rapid stirring. After the addition was complete, theslurry was stirred an additional hour. The solid was filtered and washedonce by reslurrying in water and filtering a second time. The solid wasthen reslurried in about 500 mL of water and the pH was adjusted to 10by adding concentrated ammonium hydroxide dropwise with stirring. Theslurry then was heated, with stirring, to and held at 60° C. for threehours. The slurry was cooled with stirring and filtered. The solidscollected were added with stirring to a solution of cupric acetate (6.3g, 0.03 mol) in 500 mL water. The resulting slurry was heated, withstirring, to and held at 60° C. for three hours. The slurry was cooledto room temperature with stirring and then filtered and washed on thefilter with water. The solid material collected was dried on a steambath and then calcined in air for one hour at 200° C., one hour at 350°C. and three hours at 550° C. The catalyst composition thus obtainedcontained 9.4 weight percent copper, had a BET surface area of 12.4 m²/g and had the formula Cu₀.12 Ti₀.88 O₁.88.

EXAMPLE 3

Example 2 was repeated using 4.34 g (0.024 mol) of cupric acetate toobtain a catalyst composition containing 6.6 weight percent copper. Thecatalyst had a BET surface area of 11.7 m² /g and the formula Cu₀.08Ti₀.92 O₁.92.

EXAMPLE 4

Example 2 was repeated using 3.14 g (0.017 mol) of cupric acetate toobtain a catalyst composition containing 5.0 weight percent copper. Thecatalyst had a BET surface area of 7.7 m² /g and the formula Cu₀.06Ti₀.94 O₁.94.

EXAMPLE 5

Example 2 was repeated using 1.89 g (0.010 mol) of cupric acetate toobtain a catalyst composition containing 3.1 weight percent copper. Thecatalyst had a BET surface area of 13.6 m² /g and the formula Cu₀.04Ti₀.96 O₁.96.

EXAMPLE 6

Example 2 was repeated using 0.63 g (0.003 mol) of cupric acetate toobtain a catalyst composition containing 1.1 weight percent copper. Thecatalyst had a BET surface area of 11.8 m² /g and the formula Cu₀.02Ti₀.98 O₁.98.

EXAMPLE 7

To 100 g silica (Davison 59) was added a solution of 71.2 g titaniumtetraisopropoxide in 300 mL of 2-propanol. The mixture was stirred andheated at 60° C. until all of the 2-propanol was removed. To theresulting solid was added over 10 minutes a solution of 37.7 g cupricacetate in 800 mL of 60° C. water. The mixture was stirred andevaporated to dryness on a steam bath and the solid obtained wascalcined for one hour at 200° C., for one hour at 350° C. and for threehours at 550° C. to give a black catalyst. The catalyst compositioncontained 34 weight percent copper, had a BET surface area of 222 m² /gand consisted of Cu₀.43 Ti₀.57 O₁.57 coated on silica.

EXAMPLE 8

A mixture of 51.2 g silica (Davidson Grade 59) and 106.8 g titaniumtetraisopropoxide was heated on a steam bath for one hour with stirringto give a white solid to which was added a solution of 47.13 g of cupricacetate monohydrate in 1 L of 60° C. water. The resulting slurry wasevaporated to dryness and calcined according to the procedure describedin Example 7. The catalyst composition thus obtained was a brown-black,contained 31 weight percent copper, had a BET surface area of 183 m² /gand consisted of Cu₀.39 Ti₀.61 O₁.61 coated on silica.

EXAMPLE 9

To a solution of 34.5 g cupric acetate monohydrate and 8.5 g lanthanumacetate.11/2H₂ O in 2 L water was added in two minutes 356 g titaniumtetraisopropoxide. The slurry was stirred for 30 minutes and the pHadjusted to 7.0 with concentrated ammonium hydroxide. The slurry thenwas heated, with stirring, to and held at 60° C. for 90 minutes andcooled to 25° C. in two hours. The slurry then was filtered and thegreen solid collected was dried on a steam bath in air followed bycalcining according to the procedure described in Example 7. The darkbrown-black catalyst composition contained 9.3 weight percent copper and2.9 weight percent lanthanum, had a BET surface area of 51.9 m² /g andconsisted of La₀.02 Cu₀.12 Ti₀.86 O₁.87.

EXAMPLE 10

To a solution of 59.52 g cupric acetate monohydrate and 4.25 g lanthanumacetate.11/2H₂ O in 1 L water was added in five minutes 176 g titaniumtetraisopropoxide. The mixture was cooled to 25° C. with stirring andthe pH adjusted to 7.0 with concentrated ammonium hydroxide. The slurrythen was filtered and the green solid collected was dried on a steambath in air followed by calcining according to the procedure describedin Example 7. The black catalyst composition contained 23.7 weightpercent copper and 2.3 weight percent lanthanum, had a BET surface areaof 13.1 m² /g and consisted of La₀.02 Cu₀.30 Ti₀.68 O₁.69.

EXAMPLE 11

Titanium tetraisopropoxide (44.5 g) was added in five minutes to 300 mLwater and the resulting slurry was stirred for ten minutes and heated to60° C. To the slurry was added 53.6 g powdered cupric acetatemonohydrate and the mixture was stirred at 60° C. while the pH wasadjusted to 10.0 with concentrated ammonium hydroxide. The mixture wasstirred for 15 minutes at 60° C. and then evaporated to dryness. Thesolid obtained was calcined as described in Example 7 to give a blackcatalyst composition containing 50.4 weight percent copper and havingthe formula Cu₀.63 Ti₀.37 O₁.37.

EXAMPLE 12

Titanium tetraisopropoxide (26.6) was added to 300 mL water in fifteenminutes and the slurry was stirred for one hour. The solids werefiltered off, reslurried in 300 mL water, filtered again and thenreslurried in 300 mL water. After the pH was adjusted to 10.0, theslurry was stirred and heated at 60° C. for three hours, then cooled to25° C. and filtered. The solids collected were added to a solution of31.42 g cupric acetate in 500 mL water. The mixture was heated to 60° C.and stirred at that temperature for three hours. The mixture was thencooled to 25° C., filtered and the solids obtained were washed with 50mL water. The solid material was dried and calcined according to theprocedure described in Example 7. The black catalyst composition thusobtained contained 25.2 weight percent copper, had a BET surface area of6.3 m² /g and had the formula Cu₀.32 Ti₀.68 O₁.68.

EXAMPLE 13

Example 2 was repeated using 356 g of titanium isopropoxide and 34.5 g(0.024 mol) of cupric acetate to obtain a catalyst compositioncontaining 9.6 weight percent copper. This catalyst had a BET surfacearea of 11.3 m² /g and the formula Cu₀.12 Ti₀.88 O₁.88.

EXAMPLE 14

Calcium acetate (0.42 g, 0.002 mol) was dissolved in 10 mL of water. Tothis solution was added 5.0 g of the catalyst of Example 13 withstirring. This slurry was stirred at 60° C. for five minutes and thenwas evaporated to dryness on a steam bath. The solids obtained werecalcined in air at 300° C. for three hours. The catalyst thus obtainedhad a surface area of 11.2 m² /g.

EXAMPLE 15

Example 14 was repeated using magnesium acetate (0.85 g, 0.004 mol)instead of calcium acetate. The resulting catalyst had a surface area of10.3 m² /g.

EXAMPLE 16

Example 14 was repeated using potassium acetate (0.24 g, 0.002 mol)instead of calcium acetate. The resulting catalyst had a surface area of10.0 m² /g.

EXAMPLE 17

Example 14 was repeated using lanthanum acetate (0.29 g, 0.001 mol)instead of calcium acetate. The resulting catalyst had a surface area of12.0 m² /g.

EXAMPLE 18

To 20.0 g of silica (Davison Grade 57) was added 41.6 g (0.15 mol)titanium tetraisopropoxide. The resulting slurry was heated on a steambath to give a white solid. A solution of 13.42 g (0.07 mol) of cupricacetate in 500 mL of 60° C. water was added to the solid and the mixturewas evaporated to dryness on a steam bath. The solid was calcined forone hour at 200° C., one hour at 250° C. and three hours at 550° C. Theresulting catalyst had a surface area of 182 m² /g and consisted ofCu₀.31 Ti₀.69 O₁.69.

EXAMPLE 19

The procedure described in Example 18 was repeated using 51.2 g ofsilica (Davison Grade 57), 106.8 g (0.38 mol) of titaniumtetraisopropoxide and 47.13 g (0.24 mol) of cupric acetate. Thisprocedure was performed five times and the resulting calcined solidswere combined to give a large batch of material. This catalyst had asurface area of 186 m² /g and consisted of Cu₀.39 Ti₀.61 O₁.61.

HYDROGENATION OF ESTERS

Example 20-25 describe the liquid phase hydrogenation of dimethylsuccinate (10.0 g) in methanol (100 mL) in the presence of one of thecatalysts prepared as described hereinabove. The hydrogenations wereconducted in an autoclave equipped with a 300 mL glass liner, a stirfin, thermometer, pressure gauge, a gas inlet tube and means for heatingand cooling the autoclave. In each hydrogenation procedure, themethanol, dimethyl succinate and the chemically-mixed, copper-titaniumoxide catalyst were charged to the glass liner which was positionedwithin the autoclave. The autoclave was first pressurized to 500 psiwith nitrogen and vented and then pressurized to 2000 psi with hydrogen.Stirring was started and the autoclave was heated to 200° C. (Example20) or 300° C. (Example 21-25) at the maximum heating rate. The contentsof the autoclave were stirred at 200° C. (Example 20) or 300° C.(Examples 21-25) and 2000 psi for five hours and then the autoclave wascooled and vented carefully to avoid the loss of any of the contents.

EXAMPLE 20

Using the above-described procedure, dimethyl succinate was hydrogenatedat 2000 psi hydrogen and 200° C. for five hours in the presence of 1.0 gof the catalyst obtained in Example 1. Analysis of the reaction mixtureobtained showed 2.4 percent butyrolactone and 11.2 percent1,4-butanediol.

EXAMPLE 21

Example 20 was repeated using a hydrogenation temperature of 300° C. toproduce a crude product which contained 10.7 percent butyrolactone and23.3 percent 1,4-butanediol.

EXAMPLE 22

Example 21 was repeated using 1.0 g of a catalyst prepared by repeatingthe catalyst synthesis procedure described in Example 1. The resultingreaction mixture contained 14.1 percent tetrahydrofuran, 3.2 percentbutyrolactone and 20.0 percent 1,4-butanediol.

EXAMPLE 23

Example 21 was repeated using 1.0 g of the catalyst prepared in Example2. The resulting reaction mixture contained 13.2 percenttetrahydrofuran, 4.9 percent butyrolactone and 23.9 percent1,4-butanediol.

EXAMPLE 24

Example 21 was repeated using 1.0 g of the catalyst prepared asdescribed in Example 3. The resulting reaction mixture contained 13.4percent tetrahydrofuran, 4.5 percent butyrolactone and 15.1 percent1,4-butanediol.

EXAMPLE 25

Example 21 was repeated using 1.0 g of the catalyst prepared in Example4. The resulting reaction mixture contained 6.3 percent tetrahydrofuran,5.2 percent butyrolactone and 10.5 percent 1,4-butanediol.

Examples 26-68 describe the results obtained from the gas-phasehydrogenation of methyl acetate using the catalysts provided by ourinvention and varying gas flow rates, temperatures and pressures. Theapparatus used consisted of a 1/4-inch interior diameter, stainlesssteel, tubular reactor in which was placed 1 mL (approximately 1 g) ofcatalyst held in place with quartz wool plugs above and below thecatalyst bed. The central portion of the tube was encased in an electricfurnace with a thermocouple fixed in the catalyst bed. Hydrogen andmethyl acetate vapor were fed, using Brooks flow controllers, to the topof the reactor in a hydrogen:methyl acetate mole ratio of 3:1 and 6:1.The pressure of the off-gas removed from the bottom of the reactor wasreduced to atmospheric pressure, cooled in a glycol condenser system andthe resulting liquid and gas phases were analyzed by gas chromatography.The results obtained in Examples 26-68 are given in the Table. Thenumerical designation for the catalyst (Cat) used in each example refersto the example which describes its preparation. Temperature (Temp) andtotal pressure (Press) are given in °C. and pounds per square inchabsolute, respectively. Gas flow rates are given as the gas hourly spacevelocity (GHSV) which is the mL of gas fed per hour divided by the mL ofcatalyst bed. The % methyl acetate (MeOAc) designates the mole percentof methyl acetate which is not converted to other compounds. Theconversion rates to methanol (MeOH), ethanol (EtOH) and ethyl acetate(EtOAc) are given in micromoles per g catalyst per second.

                                      TABLE                                       __________________________________________________________________________                             Rate of Conversion to                                Ex.                                                                              Cat.                                                                              Temp.                                                                             Press                                                                             GHSV                                                                              % MeOAc                                                                             MeOH                                                                              EtOH                                                                              EtoAc                                        __________________________________________________________________________    26 1   231 740 32067                                                                             60.5  3.1 1.4 2                                            27 1   251 775 32067                                                                             42.2  4.9 2.1 2.8                                          28 1   278 775 32067                                                                             56    10  4.3 5.1                                          29 1   297 800 29343                                                                             44.8  8.2 2.8 5.2                                          30 1   306 780 29343                                                                             9.2   8   3   5.4                                          31 1   306 800 28256                                                                             45.77 7.99                                                                              3.06                                                                              5.1                                          32 1   288 765 25660                                                                             57.9  11.8                                                                              6.4 3.9                                          33 13  247 760 28784                                                                             25.6  4.6 1.6 2                                            34 13  276 765 28502                                                                             34.4  10.5                                                                              4.9 4.8                                          35 7   278 770 28226                                                                             36.6  27.9                                                                              8.7 12.2                                         36 12  246 790 28179                                                                             23    5.8 3   2                                            37 12  277 830 28226                                                                             39.3  18.4                                                                              9.1 6.1                                          38 12  303 815 28502                                                                             50.6  28.7                                                                              16.2                                                                              8.4                                          39 12  242 780 16350                                                                             46.8  10.8                                                                              7.8 3.6                                          40 12  279 790 16632                                                                             32.2  17.4                                                                              7.3 6.7                                          41 5   245 800 28502                                                                             22.1  3.8 1.4 1.7                                          42 5   270 790 28502                                                                             33.8  8.3 3.3 3.9                                          43 9   249 760 28502                                                                             42.5  13.5                                                                              5.7 5.5                                          44 9   287 760 28502                                                                             69.4  31.3                                                                              21.4                                                                              7.7                                          45 8   252 745 28226                                                                             35.5  22.6                                                                              7   10.6                                         46 8   287 725 28502                                                                             60.7  56.3                                                                              33.8                                                                              16                                           47 10  247 810 28824                                                                             41.8  6.1 4   5.4                                          48 10  283 800 28224                                                                             80.7  23.1                                                                              32.5                                                                              9                                            49 18  263 765 27942                                                                             54.8  11.8                                                                              8.3 11.3                                         50 18  292 750 27942                                                                             72.8  22.3                                                                              27.9                                                                              12.7                                         51 18  274 795 16074                                                                             50    12.9                                                                              10.7                                                                              14.2                                         52 14  249 770 27942                                                                             30    1.8 1.4 1.3                                          53 14  275 775 28224                                                                             45.9  3.8 3   3.9                                          54 14  248 750 27102                                                                             47.4  1.8 0.8 0.5                                          55 17  292 750 27104                                                                             61.2  10.4                                                                              6.4 2.5                                          56 19  248 750 27384                                                                             39    10.5                                                                              2.8 4.4                                          57 19  281 760 27384                                                                             58.9  24.9                                                                              13.9                                                                              6.8                                          58 19  252 760 14676                                                                             33.6  10.5                                                                              2.7 4                                            59 19  280 750 14952                                                                             38.2  23.5                                                                              10.3                                                                              7.7                                          60 15  242 750 27384                                                                             27.5  1.4 0.9 0.1                                          61 15  279 750 27384                                                                             35.5  6.3 3.6 1.7                                          62 15  280 740 15234                                                                             26.2  3.4 1.9 0.8                                          63 16  244 750 27384                                                                             21    0.7 0.2 0.1                                          64 16  280 760 27384                                                                             19.3  1.1 0.6 0.1                                          65 16  295 750 15234                                                                             22.5  1.6 1   0.1                                          66 14  247 740 27384                                                                             28.4  3.5 1.7 1                                            67 14  283 740 27384                                                                             50.3  13.2                                                                              8.1 3.4                                          68 14  276 740 15234                                                                             36.9  9   4.4 2.6                                          __________________________________________________________________________

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications will be effected within the spirit and scope of theinvention.

What is claimed is:
 1. A catalyst composition comprising as theessential ingredients chemically-mixed, copper-titanium oxide whichcontains --Ti--O--Cu-- bonds wherein the copper oxide content,calculated as CuO, of the catalyst composition is from about 3 to 65weight percent and an oxide of lanthanum or zinc.
 2. A catalystcomposition according to claim 1 wherein the copper oxide content,calculated as CuO, of the catalyst composition is from about 8.8 to 44.0weight percent.
 3. A catalyst composition comprising as the essentialingredients chemically-mixed, copper-titanium oxide of the formula

    Cu.sub.x Ti.sub.y O.sub.z

wherein x, y, and z represent atomic ratios and x is about 0.01 to 0.75,y is about 0.99 to 0.25, and z is about 1.99 to 1.25 and an oxide oflanthanum or zinc.
 4. A catalyst composition according to claim 3wherein x is about 0.09 to 0.44, y is about 0.91 to 0.56 and z is about1.91 to 1.56.
 5. A catalyst composition according to claim 4 combinedwith or deposited on an oxide of silicon, aluminum, germanium, boron, ortin.